Various apparatuses and methods have, over the years, been developed for determining the position and speed of rotating materials or objects. For example, in the field of mechanical engineering, and more particularly the field of crankshaft mechanics, a number of apparatuses and methods have been developed in an effort to accurately determine the position and speed of a crankshaft associated with an engine to improve, for example, the engine ignition timing, and also to prevent potential engine misfire, and to more efficiently control engine emissions. However, these conventional apparatuses and methods suffer from a number of drawbacks and deficiencies.
According to one approach, a number of equally-spaced and equally-sized teeth are formed on a target wheel that rotates in unison with, for example, a crankshaft. The relative incremental rotational position and speed of the target wheel and the crankshaft is determined by sensing the passing of rising or falling edges of the teeth by a sensing element disposed in proximity to the target wheel. Since each tooth formed on the target wheel is equally-spaced and equally-sized, however, the position of the crankshaft may only be accurately determined in an incremental manner by counting each passing tooth. As a result, the relative rotational position of the crankshaft must always be determined in connection with some form of starting position or reference value.
According to another approach, equally-spaced teeth are formed along the periphery of a target wheel that rotates in unison with a crankshaft. The rotational position of the target wheel is determined by monitoring the rising and falling edges of the passing teeth, which form a bit pattern, on the target wheel via a sensing element.
According to this conventional approach, a minimum number of sequential bits must be monitored by the sensing element before the relative rotational position of the target wheel may be accurately determined, resulting in computational delay. In addition, because a minimum of six (6) sequential bits must be monitored by the sensing element, this conventional approach is incapable of determining the static position of the target wheel; namely, the target wheel must always be in motion in order for its relative rotational position to be accurately determined.
Accordingly, there is a need to be able to determine the static and dynamic angular position of a rotating member without reliance on starting positions or reference values. Moreover, there additionally exists a need to be able to determine the angular position of a rotating member at any particular point in time without having to monitor a plurality of sequential bits. It would further be desirable, particularly with the afore-mentioned needs met, to be able to detect the angular velocity and the direction of travel of the rotating member.